Highly Efficient Rhodium Catalysts for the Asymmetric Hydroformylation of Vinyl and Allyl Ethers using C1-Symmetrical Diphosphite Ligands
✍ Scribed by Aitor Gual; Cyril Godard; Sergio Castillón; Carmen Claver
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 479 KB
- Volume
- 352
- Category
- Article
- ISSN
- 1615-4150
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✦ Synopsis
Abstract
Here, we describe the successful application of novel glucofuranose‐derived 1,3‐diphosphites in the rhodium‐catalysed asymmetric hydroformylation of vinyl acetate, 2,5‐dihydrofuran and 2,3‐dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3‐ and 2,5‐dihydrofuran were the substrates, total chemo‐ and regioselectivities were achieved together with __ee__s up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP‐NMR studies of the [RhH(CO)~2~(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq‐eq fashion. The complex [RhH(CO)~2~(15)] was detected as a single isomer with characteristic features of eq‐eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO)~2~(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand.